Skip to Content

Sesen Bio, Inc.

Company NameSesen Bio, Inc.
Stock SymbolSESN
Class PeriodDecember 21, 2020 to August 17, 2021
Lead Plaintiff Motion DeadlineOctober 18, 2021

Sesen Bio is a late-stage clinical company that purports to advance targeted fusion protein (“TFP”) therapeutics for cancer treatments. Its most advanced product candidate is Vicineum (VB4-845), a locally administered TFP developed as a treatment of bacillus Calmette-Guérin (“BCG”)-unresponsive non-muscle invasive bladder cancer (“NMIBC”). Sensen Bio reported preliminary efficacy data from its ongoing Phase 3 clinical trial for Vicineum, the VISTA trial, in August 2019.

On December 21, 2020, the Company announced that it had submitted its Biologics License Application (“BLA”) to the U.S. Food and Drug Administration (“FDA”) for Vicineum for the treatment of BCG-unresponsive NMIBC.

On August 13, 2021, Sesen Bio announced that the FDA declined to approve its BLA for Vicineum in its current form. The FDA provided certain “recommendations specific to additional clinical/statistical data and analyses in addition to Chemistry, Manufacturing and Controls (CMC) issues pertaining to a recent pre-approval inspection and product quality.”

On this news, the Company’s share price fell $2.80, or 57%, to close at $2.11 per share on August 13, 2021, on unusually heavy trading volume.

Then, on August 16, 2021, Sesen Bio further revealed that “it appears that [the Company] will need to do a clinical trial to provide the additional efficacy and safety data necessary for the FDA to assess the benefit-risk profile, which is the basis for approval.”  As a result, the Company expected that it could not resubmit its BLA until 2023.

On this news, the Company’s share price fell $0.89, or 42%, to close at $1.22 per share on August 16, 2021, on unusually heavy trading volume.

Then, on August 18, 2021, before the market opened, the health and medicine news site STAT published an article entitled “Sesen Bio trial of cancer drug marked by misconduct and worrisome side effects, documents show.” Citing “hundreds of pages of internal documents” and “three people familiar with the matter,” the article detailed that the clinical trial for Vicineum was “marked by thousands of violations of study rules, damning investigator conduct, and worrying signs of toxicity the company did not publicly disclose.”

On this news, the Company’s share price fell $0.20, or 13%, to close at $1.31 per share on August 18, 2021, on unusually heavy trading volume.

The complaint filed in this class action alleges that throughout the Class Period, Defendants made materially false and/or misleading statements, as well as failed to disclose material adverse facts about the Company’s business, operations, and prospects. Specifically, Defendants failed to disclose to investors: (1) that Sesen Bio’s clinical trial for Vicineum had more than 2,000 violations of trial protocol, including 215 classified as “major”; (2) that three of Sesen Bio’s clinical investigators were found guilty of “serious noncompliance,” including “back-dating data”; (3) that Sesen Bio had submitted the tainted data in connection with the BLA for Vicineum; (4) that Sesen Bio’s clinical trials showed that Vicineum leaked out into the body, leading to side effects including liver failure and liver toxicity, and increasing the risks for fatal, drug-induced liver injury; (5) that, as a result of the foregoing, the Company’s BLA for Vicineum was not likely to be approved; (6) that, as a result of the foregoing, there was a reasonable likelihood that Sesen Bio would be required to conduct additional trials to support the efficacy and safety of Vicineum;  and (7) that, as a result of the foregoing, Defendants’ positive statements about the Company’s business, operations, and prospects were materially misleading and/or lacked a reasonable basis.

Submit Your Information

If you suffered a loss on your Sesen Bio, Inc. investments or would like to inquire about joining an action to recover your loss under the federal securities laws, please complete the form below.

An attorney will contact you at no cost to provide you information about joining the action and answer your questions. Please note that submission of this form does not by itself form an attorney-client relationship nor does filing out this form mean you have joined any lawsuit.

Shares Purchased

Number of SharesBuy DatePrice Per ShareAdd

Shares Sold

Number of SharesSell DatePrice Per ShareAdd